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arXiv 0801.3460astro-ph
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小麦哲伦星云中大质量恒星的动力学

Kinematics of massive stars in the Small Magellanic Cloud

Christopher J. Evans, Ian D. Howarth

摘要:

我们给出了小麦哲伦星云(SMC)中2045颗恒星的径向速度,这些速度是由Evans等人(2004)的2dF测量获得的。这些恒星中的绝大多数都是OBA型,追踪年轻恒星星族的动态。将样本分成特定的“棒”和“翼”样本(分别位于线的北部和南部:$δ$ = -77 $^{\circ}$ 50“+ [4 $α$”,其中$α$以分钟为单位),我们发现SMC棒中的速度梯度为26.3 +/- 1.6 km/s/deg。在126 +/-4度的位置角处。柱中的导出梯度对于两个样品之间采用的分界线具有稳健性。最大的红移出现在SMC翼,其中的速度分布似乎不同于酒吧,最有可能的结果是麦哲伦云之间的相互作用,预计已发生0.2 Gyr前。样本中所有恒星的平均速度为+172.0 +/- 0.2 km/s(与已发表的较老恒星群的结果相比,红移了约20 km/s),速度色散为30 km/s。

英文摘要:

We present radial velocities for 2045 stars in the Small Magellanic Cloud (SMC), obtained from the 2dF survey by Evans et al. (2004). The great majority of these stars are of OBA type, tracing the dynamics of the young stellar population. Dividing the sample into ad hoc `bar' and `wing' samples (north and south, respectively, of the line: $δ$ = -77$^{\circ}$50' + [4$α$]', where $α$ is in minutes of time) we find that the velocities in the SMC bar show a gradient of 26.3 +/- 1.6 km/s/deg. at a position angle of 126 +/- 4 deg. The derived gradient in the bar is robust to the adopted line of demarcation between the two samples. The largest redshifts are found in the SMC wing, in which the velocity distribution appears distinct from that in the bar, most likely a consequence of the interaction between the Magellanic Clouds that is predicted to have occurred 0.2 Gyr ago. The mean velocity for all stars in the sample is +172.0 +/- 0.2 km/s (redshifted by ~20 km/s when compared to published results for older populations), with a velocity dispersion of 30 km/s.

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